// Starting with V3, SourceMap line numbers are zero-based.
    // GWT's line numbers for Java files originally came from the JDT, which is 1-based,
    // so adjust them here to avoid an off-by-one error in debuggers.
    out.addMapping(javaFile, javaName,
        new FilePosition(javaLine - 1, 0),
        new FilePosition(startLine, startColumn),
        new FilePosition(endLine, endColumn));
    empty = true; // don't write it twice.
  }